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What have I done wrong (Mosfet Conversion)

TheRealPorkchop

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Aug 25, 2015
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Ya know, you lay out the game for awhile and your powers get weak... hmm... something, something, darkside...

Ok, so on CB Tricks we all know there's directions to do this EKL mosfet swap, and I'm using 520's and having to build my own companion parts, just to get that out the way. So I've followed those directions to a T, a very sharp T, and I can't get this radio to key a carrier. Is there something they've left out? I'm attempting to do a dual mosfet into a Galaxy 44v, yeah I know... WHY? Cause I have plenty of time to waste, that's why.

So, take a look at the pic below. That green chip looking thing is a 1000pf capacitor, it's supposed to be 1500 but that was all I had at the moment. If I install that 480k from L41 to C175, I get nothing. If I take that off, I get no carrier but I get some faint swing. I know I need to change that cap to the correct value and I will but do you see anything wrong?IMG_7209.jpg
 

The first thing I would do is check the schematic against that of a 33HML, then I would look to the 77HML and follow that to ensure the dual final conversion works, at first i'd leave it with BJT's, make sure both finals work, then mosfet convert it. You can also compare schematic of DX44V to DX99V; just some parts will not be present on non-ssb models.
I don't know of an AM/FM only dual final radio, maybe a Connex 4400?? if that used an EPT3600xx series and no SSB then that's the schematic you want to follow for your dual final conversion.
EDIT: see link below.


If you've added all the parts to make the DX44V 'dual final' then I say it might an issue with the homemade EN369FN companion part. Nothing wrong with the schematic for the EN369DR, but the other has an error & I assume the bias voltage could be off.. Just double check that you've added ALL the necessary parts for the dual final conversion first and get that cap changed out to the correct value.
[photo="medium"]4854[/photo] ..
Have ya seen this post yet--> http://www.worldwidedx.com/threads/...ors-in-the-drawing-and-the-correction.157713/
That's important if you are making your own companion.

Oh and yeah, did you order the factory replacement heatsink for a dual final model, to give that "factory fresh, 100% legit install" look and feel to the completed radio?
EDIT: the inductor by VR11 in the upper left corner is not connected?
http://www.angelfire.com/electronic/cbdoctor/dualfinalconv.html

Dual RF Final Conversion From Single Final Board
One of the best ways to increase the output of any single ended output cb radio is to add a second output transistor. This is not very practical with many units as the extra space is not available.


However, the Connex 3300 and the Galaxy DX-radios which do not have two Rf finals use the same pc board as the double final units.


Below, you will find the RF output circuit for the single output stage such as the Connex 3300, the Galaxy DX-33 and the DX-44 and the RF output circuit for the double output stage such as the DX-88 and DX-99. The various units will vary somewhat from these schematics but using these versions will work in any of the units that use the ept360014B pc board.


Armed with this information, along with a my visual layout, it becomes an easy task to convert a single-ended unit to a dual final unit.
Best Regards
 
Last edited:
here is version for the irf520 mosfet swap. you said you was looking at the ekl2030 pages. take a look at this paper work link. verify you have it done like this one.

http://www.cbtricks.com/miscellaneous/fet_papers/mosfet_conv/graphics/3600xxx_am_fm_mosfet.pdf

I did look at that, only problem is that's for a single final and I'm trying to convert to dual. I'm following the method from there for dual's using the EKL mosfets except I'm using IRF's instead. I've actually got it to key but it'll only do 1 watt, high is maybe 4 if I'm lucky. I just finished a Connex 3300 that was a single final and I converted it to duals except I used the entire parts list for a true dual final radio. On this one, I wanted to just do the "half-ass" method by following those directions and not having to add in all the parts to a factory install. I do have the factory style heatsink to make it look "factory". Yeah, we all know that a DX44v never came with dual finals but hopefully this one will.


LeapFrog, no bro I hadn't seen that and thanks for pointing that out. I'll make the changes. I believe the DR is the part I'm having to build myself for this one, I think the FN is actually the EKL part, maybe it's wrong too though? I'll redo those and we'll see what happens.

When I get to the step on putting the 480K from L45 to C175, that's when things go all to pieces.
 
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So, update here. I thought I'd posted that earlier but I guess my pudgy little fingers didn't hit the right key or something...

I can't set the deadkey higher than 4 watts. I changed the companion parts around and that didn't change anything either. Not that I want the deadkey higher than 4 watts but that's setting it on HIGH... I'm pretty sure I should be able to get it to at least 6-8 watts and low on about 1-2 watts... not happening with this devil radio.

See boys and girls, this is what happens when you modify something that was working just fine to start with... idle hands leads to the devils work, hahahahaha.

Ok, so I'm setting this one aside I guess unless one of you guys that's much smarter than me has a suggestion. I'm gonna order the parts to do a full conversion like it would've been done at the factory if they'd decided to make a 44v dual final, which they didn't, which should tell me something but it doesn't. I shall report the outcome once those parts gets here... not that anyone cares or is fooling with such old radios but I have a lot of time to waste. I'm like the cable guy, I get bored... I mean REALLY bored...
 
Do you ever sleep? I thought I had weird sleep habits but dag-on Sonoma...

I must be a crackbaby cause I don't find this stuff like you do and I comb CB Tricks all the time... weird.

That might be what I needed, thanks bro. Plus, ordering the parts and doing it that way would be better in the end I believe. I don't know why I'm doing this other than the fact that I just have time to waste and nothing better to do.

I end up with all these radios with issues of some sort, helps to pass the time and take my mind off things, otherwise, it's a total waste of time and effort I think.
 
I have a hard time sleeping. I only sleep about 2 hours a day in most cases. some time I will go 2 days with out sleep. I search through the forums all the time since my wife is sleeping. I am retired now so not much sleep for some reason. when I use to work I was on night shift and would get home about 6 AM and would go to bed and be up at about 9 to 10 AM and then go out and do things out side then head back to work at 4 PM. Doctors say I need to sleep more but I have not been able to sleep much since about 1980.
I just got where that is all my body wants to sleep. they have even tried giving me sleeping pills and it did not work.
hopefully with the last item I left you will help you get it going.
also you might even try the little ceramic insulators behind the finals. the factory thin ones do not work real good on the mosfet change. they cause a capacitance problem on some radios and the ceramic ones help to take care of the problem. Rick from euro radio that helped Bennie with these mods told me this when I was putting dual finals in a texas ranger 696fd1 radio. would not swing past 20 watts with dual finals and the flimsy insulators. put the ceramic in it and it would swing over 40 watts. I was surprised at this.
just some thing you might think about since you are doing the mod.
 
the forum has some very good info about the dual final mods but since it is down I can not get into it to find any of them. it will still let you do a search but can not find what I was trying to find for you.
 
Yea, seems like I've encountered that before about the insulators or something along those lines. The ones I'm using are ceramic, I just like the look of them to be honest.

Wow on the sleep Sonoma, just wow. That's weird and wild. I don't have room to talk, I don't sleep much either but mine is stress related.

And yup, can't get into the forum since the database crash or whatever happened, real nice ain't it? If I could figure out why I can't get a high side key higher than about 4 watts, I'd be happy with what it's doing now. It shouldn't bother me but I just have this feeling that it should do more and possibly it's holding me back a little on the end results. We'll see though... Maybe it's getting time to revisit the 2290 in a radio again...
 
I had a galaxy 959 I could never get it higher than 18 watts one time. put the whole final setup from a base radio I think it was a 2517, the base would do over 40 watts and the 959 for some reason would not do over 18 with all the same parts. even changed all the components in the mic circuit for more audio. never did figure out why it would not swing more. just put it back to a single final and it would do the same 18 watts. I spent 2 full days on that radio and just forgot about it. after changing the parts in the mic circuit it had a lot more audio than the stock 959. they kill the audio on them to meet FCC's guide lines for a cb radio. the 959 is just choked off.
 
you are talking about a 2290 in the radio, I have a 44 hml that I put the little 4 pill stinger board in it from RM amps and it really does good. right at 100 watts. only problem is you have to pull the stock speaker out of it. no problem for me since I always use an external speaker. a couple guys claim the stinger board in a SSB radio will push about 175 watts on SSB. that would be cheaper than a 2290 pill in it. the stinger has mosfets in it. if I have to change them I put 13n10 mosfets back in them. they give a little more out put than the stock finals. for a while you could by the stinger board for just under 50.00 new shipped. was not a bad price.
 
Not exactly, I meant adding a 2290 into the back of the radio. I posted the how-to on the shiny metal forum a long time ago. I'll dig it up and post it here too. It was very primitive and rough, I'm sure someone could refine it and make it better.

I had a 959 once that I attempted the same thing in, epic fail. I don't know what they do to that radio but they definitely choke it down and keep it down. It'd be a nice little radio if you could juice it up a little without having to resort to an amp. I like the AD-203 myself, I've installed several of them and they work really nice.

The older stinger boards, those things got hot as the sun. Had a lot of problems with those things, not so much with the 203's. The PCB-60 is a good one for a 959, it'll put it at 40 PEP and doesn't require the speaker to be removed.
 

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